Creamy Chicken and Wild Rice Soup

Ingredients

• ¼ cup butter
• ½ large yellow onion ( peeled and chopped)
• 3 medium carrots ( peeled and diced)
• 8 ounces button mushrooms (sliced)
• 3 stalks celery (diced)
• 1 teaspoon salt
• ½ teaspoon pepper
• 3 cups cooked chicken (shredded (see note))
• 4 cups chicken broth ( (or chicken stock))
• 1 tablespoon all-purpose flour
• 1 cup heavy cream
• 1 cup long grain and wild rice mix
• Salt and pepper (to taste)
• Flat-leaf parsley (chopped, for garnish)